I have a 2002 F-150 with the 4.6L v8 that is having some starting issues. For a while now I've had issues getting it too start right away. It turns over fast but would never fire. The usual fix was too turn key off for a few seconds, turn key back on for a few seconds (3-5), then attempt to start and it would fire right up. The problem has now become the engine will fire, stumble, stall. When it doesn't do this it continues to be the same hard start condition. This morning it took about 8 - 10 attempts for it to finally start and idle as normal. Once the engines finally starts and idles normally, it runs like a top. No hesitation, no stall, normal power, etc. The truck only has 125,000 miles on it but I'm wondering if sensors are too blame. I've read threads that indicate various sensors could be too blame... (crankshaft, camshaft, throttle position). I've cleaned the MAF, IAC, and throttle body before (about 1.5 yrs ago) just as good maintenance. This didn't remedy the problem then and I doubt it will now but I plan on doing all of this when I get off work today. My CEL light does not come on, so, my question to all of you experts is this...

Should I just go ahead and replace the sensors I mentioned on top of cleaning others? Also, what else could be causing this condition? Could the fuel pump be too blame? Would it run perfectly fine once it starts as stated if fuel pump were faulty?

Ready to finally remedy this hard starting condition once and for all.

Thanks in advance,
Chris

P.S. The hard start condition seemed to be more noticeable when the engine was warm.... Meaning, it used to start fine every morning before work but would turn over without starting if I had to leave mid morning.

 

You should not replace anything unless you have data that indicates indicates the part is defective, otherwise, you're just guessing. ATM, you have ZERO data so that's what you should replace - nothing, until you have specific data that indicates what or where the problems is.

Start with connecting a fuel pressure gauge to the fuel rail and MEASURE the pressure. Report specific results and observations. That way, you have your first data point and a direction to pursue.

 

I'll get on this asap. What pressures should I be looking both with key on and running?

Thanks,
Chris

 

28 to 40.

When was the last time you changed the fuel filter?

 

It's been a few years since I changed the fuel filter but not many miles. I don't put anywhere the average 10k - 15k per year on it. I'll go ahead and change just to be sure though. Will be checking fuel pressure later this afternoon and report back.

 

Here's some data, mostly bad I think... Got a fuel pressure tester from Auto Zone, hooked up to schrader valve, cycled key on and off a few times waiting about 10 seconds between each cycle. Never got above 10 - 12. 2 strange things... 1. A very strange noise from fuel pump I'm assuming while cycling on and off. Could have been happening for a while just never noticed. 2. Truck cranked without hesitation and rose to about 16 but stopped there. Seems like these low pressures would not allow to start and idle smoothly. I'm guessing I'm looking at a new fuel pump??? Bad noises, bad pressures, etc. I grabbed a new fuel filter while at auto zone, I guess I could install it but that would do much to help the noise coming from the tank area. I've got a recording of the noise but not sure how to get it on here so everyone can hear it.

 

I now question all of the data I thought I had collected. I replaced the fuel filter, hooked the pressure tested back up, and it now reads 0 psi even though the truck cranks and idles without any problems. I'm guessing the pressure tester from auto zone is a pos and didn't give me an accurate reading the first time. Maybe I can find a shop that will give me a reading for free. I've yet to hear the strange noise from the fuel pump again but will continue to listen for it each time I crank my truck.

 

I'd try one more time with the pressure gauge. Maybe it wasn't hooked up quite right the before. I think all the parts stores loan the same tools now if you need another one.
I borrowed the gauge from my local Autozone and it was broken. The pressure relief plunger had come out. So, I bought one, about $25 plus shipping. My pressure was 30psig.

 

obviously since it's running fuel is traveling through the lines, is the valve functioning properly? Not sure how you could verify without spraying fuel everywhere (maybe somebody else has a suggestion for that?) or you could try exchanging the tester for a different one from autozone, or another parts store that loans tools? Loan-a-tools take a lot of abuse, I've returned a loaner for a different one and they've given me a brand new one, so maybe you got a broken pressure tester?

 

Sorry for the late update... Finally got a pressure tester that worked and it read 35psi and cranked multiple times yesterday without issue. Can a fuel pump provide bad pressure intermittently? Anything else I should be looking at? Should I just check the pressure again when the hard start issue returns? I'm sure the hard start issue will return, its been happening for quite a while now.

Plugs and COPS are about 2 years old, fuel filter is brand new. Injectors maybe? Any good way to clean these?

Thanks in advance...

 

You have to keep chasing until you see a link with a no start.
If there are no codes, do not begin to replace other parts by hoping.
The fuel system has no codes or senors to tell you of an issue.
You have to chase a fuel pressure issue with a gauge over time if it's intermittent, to be sure that's the cause.
Rule this out or the cause, first.
.
Other cause of no start with no codes.
1. PCM relay contacts or seating.
2. Crank sensor plug seating.
3. Pats issue but with a flashing Theft light.
4. Ignition switch contact faults.
You see from this that you need to pay attention and pin point it first.
Good luck.

 

FWIW.....In my other thread here I had a problem where the truck (03' 5.4) didn't start. I did not get a check engine light but a P0231 code (Fuel Pump Secondary Circuit Low) showed up on the scanner. Point being just because you didn't get a CEL doesn't mean a code was not captured. You never mentioned if you hooked up a scanner and checked. I might suggest doing that just to confirm.

I changed out the fuel pump relay yesterday and so far so good.

 

No problems over the weekend, started as it should each time. I don't want to just start throwing parts at it but I also don't want to be stranded somewhere. This has been going on for quite a while, roughly 3 yrs or so, and got considerably worse for a short period about a month ago.

I'll stop by autozone at some point and have them put a code reader on it. Thanks for all the suggestions thus far, I'll keep chasing and hopefully catch something at some point.

 

Stopped by AutoZone at lunchtime and there were no codes. Guess I'll wait till the problem resurfaces...

 

If there is an issue with power in some form via fuse seating, PCM relay seating or it's contacts that opens power to the PCM; the PCM cannot detect any of these issues because it depends on that power to work and cannot look backward at them or set any codes.
This why you need to look in those areas.
With the engine running see if there is any reaction to movement in those areas especially when the issue is present.
Good luck.